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United States Patent |
5,142,598
|
Tabone
|
August 25, 1992
|
Fiber optic connector having snap ring adjustment means
Abstract
A fiber optic connector of the so-called D-4 type incorporating means for
incrementally adjusting the fiber core supporting ferrule with respect to
an alignment projection which engages a corresponding recess in an adapter
when the connector is engaged with the adapter. In addition to the usual
radially arranged slots in a key member which are selectively engaged by a
corresponding projection on a ferrule supporting element during the
adjustment procedure, the device includes a slidably mounted snap ring
which is pushed into locked engagement to prevent loss of final
adjustment. The snap ring is moved to this position by a selectively
engageable adjustment tool which also serves as a protective cap.
Inventors:
|
Tabone; Peter P. (Kings Park, NY)
|
Assignee:
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Porta Systems Corp. (Syosset, NY)
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Appl. No.:
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751868 |
Filed:
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August 28, 1991 |
Current U.S. Class: |
385/78; 385/53; 385/77 |
Intern'l Class: |
G02B 006/36 |
Field of Search: |
385/78,76,77,53,55
|
References Cited
U.S. Patent Documents
4726647 | Feb., 1988 | Kakii et al. | 385/78.
|
4787699 | Nov., 1988 | Moulin | 385/80.
|
5052774 | Oct., 1991 | Bulman et al. | 385/76.
|
5054879 | Oct., 1991 | Brown | 385/78.
|
Primary Examiner: Lee; John D.
Assistant Examiner: Heartney; Phan Thi
Attorney, Agent or Firm: Temko; Charles E.
Claims
I claim:
1. A fiber optic plug connector comprising: a selectively engageable tool
element, a ferrule supporting inner body element having first and second
ends and a cylindrical outer surface having an annular locking recess
therein, a ferrule supported at said first end thereof, a resilient
retaining ring surrounding said inner body element and selectively
engaging said locking recess, a cable engaging body element coupled in
coaxial relation to said second end of said inner body element, a stop
bushing surrounding said first end of said inner body element, a key body
having first and second ends surrounding said inner body element and stop
bushing and having an axially oriented aligning projection extending from
said first end, said second end defining a plurality of accurately
arranged slots; said cable engaging body element having corresponding
projections selectively engaging said slots; a compression spring
interconnecting said stop bushing and said key body and resiliently urging
said stop bushing against said retaining ring; said tool element having an
operative end thereof selectively engaging said retaining ring for the
transmission of longitudinal movement to said retaining ring toward said
locking recess; said movement serving to retain engagement of said key
body with said cable engaging body element to prevent relative rotation
therebetween.
2. A plug connector in accordance with claim 1, in which said tool element
includes a first axially disposed bore surrounding said inner body element
at said first end thereof, and a communicating counter bore providing
clearance for said ferrule.
3. A plug connector in accordance with claim 1, in which said stop bushing
is formed of synthetic resinous material having a low coefficient of
friction, to facilitate relative rotation of said retaining ring.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to the field of signal transmission
through fiber optic cables, and more particularly to an improved connector
plug of the so-called D-4 type which is permanently engaged to a
terminated fiber, and selectively coupled to an adapter at one end
thereof, the adapter coupling to a similar plug at another end thereof
whereby the terminated fibers of each connector are placed in abutted
coaxial relation for light transmission therebetween. Devices of this
general type are well known in the art, and the invention lies in specific
constructional details relative to incorporated means for aligning the
optical centers of the fibers as closely as possible for maximum light
transmission.
The known D-4 type plugs include means for adjusting the rotational
relation between the terminated fiber and an alignment projection on the
body of the plug for this purpose. The adjustment procedure usually
includes the making of a first adjustment, the assembly of a pair of
connectors to the adapter, following which a quantitative test of light
transmission is made using a meter. One of the connections is then
disconnected, and the above described adjustment is made in serial
increments with a trial measurement for each increment until maximum light
transmission is obtained.
SUMMARY OF THE INVENTION
Briefly stated, the invention contemplates the provision of an improved
so-called D-4 type incorporating means for incrementally adjusting the
fiber core supporting ferrule with respect to an alignment projection
which engages a corresponding recess in an adapter when the connector is
engaged with the adapter. In addition to the usual radially arranged slots
in a key member which are selectively engaged by a corresponding
projection on a ferrule supporting element during the adjustment
procedure, the device includes a slidably mounted snap ring which is
pushed into locked engagement to prevent loss of final adjustment. The
snap ring is moved to this position by a selectively engageable adjustment
tool which also serves as a protective cap. When the tool is subsequently
removed, the adjustment cannot be altered without use of another
specialized tool.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, to which reference will be made in the specification,
similar reference characters have been employed to designate corresponding
parts throughout the several views.
FIG. 1 is a longitudinal central sectional view of a plug connector
embodying the invention.
FIG. 2 is a longitudinal sectional view of a combination protective cap and
tool forming a part of the embodiment.
FIG. 3 is an end elevational view as seen from the right hand portion of
FIG. 2.
FIG. 4 is a longitudinal sectional view of an inner ferrule supporting body
element.
FIG. 5 is a side elevational view of a snap ring member.
FIG. 6 is a longitudinal sectional view of a stop bushing.
FIG. 7 is a longitudinal sectional view of a coupling nut.
FIG. 8 is an end elevational view as seen from the right hand portion of
FIG. 7.
FIG. 9 is a longitudinal sectional view of a cable engaging body element.
FIG. 10 is an end elevational view thereof as seen from the left hand
portion of FIG. 9.
FIG. 11 is a longitudinal sectional view of a key body.
FIG. 12 is an end elevational view thereof as seen from the right hand
portion of FIG. 11.
DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENT
Referring to FIG. 1 in the drawings, in accordance with the invention, the
device, generally indicated by reference character 10 comprises broadly: a
cap and tool element 11, a ferrule supporting inner body element 12, a
retaining ring 13, a stop bushing 14, a coupling nut 15, a cable engaging
body element 16, a key body 17, a ceramic ferrule 18, and a tension spring
19.
The cap and tool 11 is preferably formed of molded nylon, and includes a
head member 20 and an elongated shank member 21. The head member 20 is
bounded by an outer end surface 22, a cylindrical surface 23 and a radial
surface 24. The shank member 21 includes a cylindrical tube member 26
having an outer surface 27 extending between an inner end 28 and an outer
end 29. A cylindrical bore 30 (FIG. 3) engages the body 12 and an inner
bore 32 which surrounds the ferrule 18. A pair of planar slots 33 and 34
(see FIG. 3) extend axially from the free end of the shank member 21, and
selectively contact the retaining ring 13, as will more fully appear.
The ferrule supporting inner element 12 is preferably formed as a precision
die casting, and is of generally tubular configuration. It includes an
outer surface 42 extending between first and second ends 43 and 44 and
defines a cylindrical bore 45 and communicating counter bore 46. The first
end 43 is provided with annular rings 47 for the force fitting of the
element 16. The second end defines an annular recess 48 selectively
engaging the ring 13. An annular ring 49 retains the ring 13 in an initial
position, and includes a camming surface 50 which facilitates movement of
the tool element 11 therepast.
The retaining ring 13 is illustrated in FIG. 5, and is preferably formed
from nickel plated beryllium copper. It includes a circular ring portion
55 terminating in a pair of tool engaging terminals 56 and 57 which define
a spreadable gap 58 therebetween. Rotation is facilitated by the fact that
the ring rides against the stop bushing 14, which being formed of a smooth
relatively hard synthetic resinous material offers little frictional
resistance to such rotation.
The stop bushing 14 (FIG. 6), as mentioned above, is formed as a synthetic
resinous molding, and includes a cylindrical body 61 bounding by inner and
outer surfaces 62 and 63. One end 64 mounts a radially extending flange
65, the outer surface 66 of which bears against the ring 13.
The coupling nut 15 is also formed as a zinc die casting, and is of
generally conventional configuration, including a cylindrical sidewall 71
bounded by an outer surface 72 and an inner surface 73 having a threaded
portion 74 which engages corresponding threads (not shown) on an adapter.
An end wall 75 defines a centrally disposed bore 76.
The cable engaging body element 16 (FIG. 9), again, is a zinc die casting,
and includes a main body portion 80 having a knurled outer surface 81
which is manually engaged during adjustment. An end surface 82 mounts
first and second locking projections 83 and 84. A first bore 85
frictionally engages the body element 12. End surface 86 merges with a
hollow tubular projection 87, an outer surface 88 of which defines annular
rings 89 and 90 for engaging a synthetic resinous strain relief member
(not shown) of known type. A relatively large bore 91 communicates with a
conical bore 92 and smaller bore 93 aligned with the bore in the ferrule
18.
The key body 17, a die casting, includes a tubular body 101, an outer
surface 102 of which includes a threaded portion 103 which serves to
retain the coupling nut 15. A first end 104 includes a projection 105
which engages the adapter in known manner. A centrally disposed bore 106
leads to a smaller bore 107 in an end wall 108, an outer surface of which
mounts a plurality of integrally formed accurately spaced projections 109
separated by slots 110 which selectively engage the projections 83 and 84.
The ferrule 18 is preferably of known ceramic type. A first end 116 engages
the inner body element 12. A centrally disposed bore 117 supports a fiber
core (not shown) which extends to an outer surface 118 at an opposite end.
The tension spring 19 is conventional, a first end 120 engaging the key
body, and a second end 121 engaging the flange of the stop bushing.
Aside from the retaining ring 13, the device is maintained in assembled
condition solely by frictional engagement of certain of the component
parts. Assembly is commenced by first sliding the ring 13 upon the outer
surface of the inner body element 12 to the position shown in the upper
portion of FIG. 1. Next the stop bushing 14 is engaged from an opposite
end and moved to engage the ring 13. The spring 19 is then engaged to
surround the stop ring, following which the key body is applied to
surround the spring.
Next, the inner body element 12 is force fitted to the cable engaging body
element 16 to maintain all of the above mentioned parts in position as
shown in FIG. 1. In this condition the coupling nut 15 is fitted by
running the threads on the inner surface of the same past the threads on
the key body. The fiber cable may be then fitted in known manner and the
terminal end of the core polished as known in the art.
The process of matching the optical access of the core with respect to the
optical access of another fiber in a mating plug connector is performed in
a conventional manner. This process normally requires assembly of the
device with the adapter along with the assembly of the corresponding plug
connector and reference cable, following which an initial light
transmission test is made using a meter connected to the reference cable.
Next, the device 10 is discontinued and the ferrule is rotated through a
predetermined increment by pulling and rotating element 16 against the
action of spring 19. Another trial is made, and the result noted. The
process is continued until optimum light transmission is obtained,
following which the device is once again disconnected from the adapter,
and the tool 11 is pressed inwardly to move the retaining ring 55 from the
position shown in the upper portion of FIG. 1 to the lower portion of FIG.
1 wherein it enters the recess 48. This movement will prevent further
longitudinal movement of element 16 sufficient to allow rotation. The
device may then be disconnected and reconnected to an adapter without loss
of this adjustment. Once this condition has occurred, the tool 11 is
incapable of opening the ring 13, and serves merely as a protective cap
for the ferrule. However, the ring can be opened if necessary by use of a
separate tool (not shown) which engages the terminals 56-57 and then
spreads the ring to allow it to be moved out of the recess and slid back
to the original position against the shoulder of bushing 14.
I wish it to be understood that I do not consider the invention to be
limited to the precise details of structure shown and set forth in this
specification, for obvious modifications will occur to those skilled in
the art to which the invention pertains.
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